Submerged Coils - Heat Transfer Coefficients

Heat transfer coefficients for steam and hot water coils submerged in oil tanks.

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Oil tank - heating coils

The overall heat transfer coefficients for steam coils with medium pressure - or hot water coils or pipes - submerged in oil or fat:

Submerged Coils - Heat Transfer Coefficients
Type of Coil	Heat Transfer Coefficient - U -
Type of Coil	(W/m^{2 o}C)	(Btu/hr ft² ^oF)
Steam to Aqueous Solutions, agitated	800 - 1200	140 - 210
Steam to Aqueous Solutions, natural convection	340 - 570	60 - 100
Steam to Light Oil, natural convection	170	30
Steam to Heavy Oil, natural convection	85 - 115	15 - 20
Steam to Heavy Oil, agitated	140 - 310	25 - 55
Steam to Fat, natural convection	30 - 60	5 - 10
Steam to Organics, agitated	510 - 800	90 - 140
Hot Water to Oil, natural convection	34 - 140	6 - 25
Hot Water to Water, natural convection	200 - 370	35 - 65
Hot Water to Water, agitated	480 - 850	90 - 150
Heat transfer oil to Organics, agitated	140 - 280	25 - 50
Salt brine to Water, agitated	280 - 630	50 - 110
Cooling Water to Glycerine, agitated	280 - 430	50 - 75

Example - Heat Transfer from a Steam Coil

A 50 mm steam coil with outside diameter 60.3 mm(0.0603 m) and length 10 m with 1 bar absolute pressure and steam temperature 120 ^oC is submerged in an oil bath with temperature 50 ^oC.

The surface area of the coil can be calculated by multiplying the pipe circumference with pipe length as

A = π (0.0603 m) (10 m)

= 1.89 m²

From the table above the heat transfer coefficient is 170 W/m² ^oC for "Steam to Light Oil, Natural Convection". The heat transfer can be calculated as

Q = (1.89 m²)((120 ^oC) - (50 ^oC))(170 W/m² ^oC)

= 22491 W

Submerged Coils - Heat Transfer Coefficients